The present invention relates generally to the vacuum cleaner art and, more particularly, to a motor protection system for a vacuum cleaner.
A vacuum cleaner is an electro-mechanical appliance utilized to effect the dry removal of dust, dirt and other small debris from carpets, rugs, fabrics or other surfaces in both domestic and industrial environments. In order to achieve the desired dirt and dust removal, a rotary agitator is provided to beat dirt and dust from the nap of the carpet and a pressure drop or vacuum is used to force air entrained with this dirt and dust into the nozzle of the vacuum cleaner. The particulate-laden air is then drawn through a bag-like filter or a cyclonic separation chamber and filter combination which traps the dirt and dust, while the substantially clean air is exhausted by an electrically operated fan that is driven by an on board motor. It is this fan and motor arrangement that generates the drop in air pressure necessary to provide the desired cleaning action. Thus, the fan and motor arrangement is commonly known as the vacuum or suction generator.
Many advanced, high performance vacuum cleaners incorporate a dual motor system. Accordingly, a separate agitator drive motor is provided in addition to the motor of the suction generator. At various times, the operation of the rotary agitator is not desirable for the most efficient cleaning performance. For example, when using an above floor attachment, to clean e.g. beneath the cushions of a sofa, operation of the rotary agitator serves no useful function and, in fact, causes unnecessary wear of the operating mechanism and the underlying carpet. As another example, operation of a rotary agitator during bare floor cleaning may cause turbulence that tends to push dust and dirt ahead of the vacuum cleaner nozzle thereby interfering with efficient cleaning. As such, deactivation of the agitator is also desired during bare floor cleaning. Hence, the ability to selectively de-energize the agitator drive is a desirable feature.
In addition, the agitator motor must be protected from overheating and/or overloading under adverse operating conditions which may arise in order to extend the service life of the vacuum cleaner. For example, a sock or other object may lodge between the rotary agitator and the nozzle housing partially or fully binding the agitator. Such a situation may not be immediately apparent to the operator. Accordingly, a xe2x80x9csmartxe2x80x9d vacuum cleaner which automatically detects and compensates for such a condition would be of significant benefit.
In accordance with the purposes of the present invention is described herein, an improved upright vacuum cleaner is provided. That vacuum cleaner incorporates a housing including a handle assembly and nozzle assembly. A suction fan and cooperating suction fan drive motor are carried on the housing. A rotary agitator is held in the nozzle assembly and a separate agitator drive motor is carried on the housing and functions to drive the rotary agitator. In addition, a motor control and protection circuit is provided. That motor control and protection circuit is characterized by a handle switch with a handle actuator cooperating with the handle switch to energize the agitator motor when the handle is displaced to an upright storage position.
In accordance with a further aspect of the present invention, the motor control and protection circuit may also include an above-floor switch and an above-floor actuator cooperating with the above-floor switch to de-energize the agitator drive motor when the nozzle assembly is displaced a predetermined distance above the floor. This may occur when, for example, the vacuum cleaner is adjusted for bare floor cleaning or the handle is moved to the fully upright storage position.
The vacuum cleaner may also further include a hose switch and a hose actuator cooperating with the hose switch to de-energize the agitator drive motor when an end of the vacuum cleaner hose is released and manipulated such as necessary when using the separate cleaning utensils for above floor cleaning.
Still further, the motor control and protection circuit may include a selector switch and a selector actuator cooperating with the selector switch for selectively de-energizing the agitator drive motor independent of the suction fan drive motor. Preferably, that selector actuator is positioned on the nozzle assembly where it may be easily and conveniently manipulated by engagement with a foot or toe of the vacuum cleaner operator.
In accordance with yet another aspect of the present invention, the motor control and protection circuit may also include a circuit breaker adapted to interrupt the power to the agitator drive motor if the current drawn by that motor exceeds a predetermined first value. Such a situation may occur, for example, in the event the rotary agitator becomes jammed through engagement with the fringe of a rug or other object that wedges between the agitator and the nozzle assembly thereby preventing or restricting the rotation of the agitator.
Additionally, the motor control and protection circuit may include a temperature sensor switch to interrupt power to the agitator drive motor if the temperature of the agitator drive motor exceeds a predetermined second value. This may, for example, occur if the vacuum cleaner is being operated continuously at peak power in a harsh, dusty operating environment where the cooling air flow over the agitator drive motor becomes restricted.
Advantageously, the motor control and protection circuit of the present invention provides trouble free operation of the agitator drive motor in a vacuum cleaner incorporating separate suction fan and agitator drive motors. More specifically, the agitator drive motor is protected from overloading and overheating at all times under all operating conditions. Additionally, the most efficient performance of the vacuum cleaner is ensured as the agitator drive motor is de-energized when operation of the rotary agitator is not of benefit. Thus, for example, when the hose is disconnected at one end by the operator for purposes of above floor cleaning, the agitator drive motor is de-energized to save energy and wear and tear on both the vacuum cleaner and the floor surface being engaged by the rotary agitator. Similarly, de-energization takes place when the handle of the vacuum cleaner is placed in the upright storage position and the vacuum cleaner is not being manipulated to-and-fro to clean the floor. Similarly, the agitator drive motor is de-energized when the nozzle assembly is adjusted to a height for bare floor cleaning. By de-energizing the agitator drive motor in this mode, dust and debris are moved under the force of negative pressure from the floor through the nozzle assembly and hose toward the dust bag where they are collected without any interference from the rotary action of the agitator. Further, a convenient on-off switch is provided to allow the operator to individually select de-energization of the agitator drive motor under substantially any operating condition where that mode of operation is deemed desirable. Thus, the vacuum cleaner of the present invention provides unmatched versatility and allows use at maximum efficiency under substantially any foreseeable operating conditions.
Still other objects of the present invention will become apparent to those skilled in this art from the following description wherein there is shown and described a preferred embodiment of this invention, simply by way of illustration of one of the modes best suited to carry out the invention. As it will be realized, the invention is capable of other different embodiments and its several details are capable of modification in various, obvious aspects all without departing from the invention. Accordingly, the drawings and descriptions will be regarded as illustrative in nature and not as restrictive.